The present invention relates generally to a modular plug for data transmission. More particularly, the present invention relates to a modular plug for high speed data transmission in support of multi-gigabit Ethernet protocols.
The use of modular plugs and jacks for data transmission is known. Plugs are attached to ends of an electrical cable connecting electronic devices such as switches or routers in data centers or computers in offices. The cables have multiple conductors, or wires. For Ethernet protocol connectivity, typically eight wires are used. While the cable is terminated by plugs, the electronic equipment must have jacks corresponding to the plugs. Plugs and jacks are designed to be able to mate to provide both mechanical and electrical coupling. International standards govern the mechanical dimensions of the plugs and jacks.
A common mechanical connector configuration known as RJ45 allows utilization of the existing networking equipment through a feature called auto-negotiation. During the auto-negotiation process, the connected devices assume master-slave relation and agree on the maximum speed for data to be transmitted. The jacks, cable, and plug must be able to support the Ethernet protocols and may affect the auto-negotiation. If any component is designed for the older Ethernet speeds, it will force the newer and faster networking equipment to run below its intended speed. All known modular plugs that work in a wide data transmission spectra (such as from 10 to 2000 MHz) cause some degradation of the signals.
Ethernet protocols divide the electromagnetic signals into four streams. These streams are transmitted over the same cable. Thus, with a mated connector pair, there are four streams or channels of signals operating simultaneously. The unwanted interaction of these signals is called near end cross talk (or NEXT). The NEXT must be minimized to allow substantially error-free transmission of data. The most common method of reducing NEXT is through compensation. Compensation can be provided by creating signals of similar amplitude but opposite polarity from the NEXT signals that are inherently present at the interface between the jack and the plug. A compensating reactance that is defined near the plug-jack interface can be used for this purpose.
Signal degradation at high frequencies is caused by one or more of several potentially mutually dependent issues. Introducing compensation far away from the interface may cause an unpredictable phase shift of electromagnetic signals traveling within the jack and plug connection. The plug contact blades have high intrinsic self-inductance and uncontrolled and relatively low capacitance between adjacent contacts. Known designs also do not allow for control of the interaction of the cable pairs within the plug. The distance between the cable terminations and the contacts is overly long in existing designs. Finally, most of the existing plug designs attempt to provide easy termination in the field at the expense of transmission performance.